1. Field of the Invention
The present invention relates to a rotationally-operated input device that is used for operating parts of various types of electronic device and outputs rectangular wave signals in response to rotating operation of the operating shaft thereof.
2. Background Art
In recent years, with the size and thickness reduction of various types of electronic device, such a device has had enhanced multi-functionality. Accordingly, an increasing number of rotationally-operated input devices are mounted on an insulating substrate to be rotated in parallel with the surface of the insulating substrate. Such a conventional rotationally-operated input device is described with reference to FIGS. 8 through 10.
FIG. 8 is a sectional view of a conventional rotationally-operated input device. FIG. 9 is an exploded perspective view of the conventional rotationally-operated input device. FIG. 10 is a diagram showing a circular recess in a contact case of the conventional rotationally-operated input device. With reference to FIGS. 8 through 10, contact case 10 made of an insulating resin has circular recess 11 open to the front face thereof. Cylindrical protrusion 12 is formed at the center of the bottom face of circular recess 11. At the center of cylindrical protrusion 12, bearing hole 13 is provided. Along the outer periphery of cylindrical protrusion 12, common electrode 20 is exposed. Outside of common electrode 20, signal electrodes 30 and 40 are insert-molded in an exposed state.
Common electrode 20 is exposed in a semi-circular ring shape. Extension 22 extending from the intermediate position of the semi-circular shape connects common electrode 20 to common terminal 21 that projects downwardly from the outer peripheral wall forming circular recess 11 of contact case 10. As shown in FIG. 10, signal electrodes 30 are formed in a position on the left side of extension 22 of common electrode 20, in an angular range of approximately a half the angular range of exposed common electrode 20. The plurality of signal electrodes 30 is exposed radially with respect to the center of cylindrical protrusion 12 to form A-phase signal electrodes. Signal electrodes 40 are formed in a position on the right side of extension 22 of common electrode 20, in an angular range of approximately a half the angular range of exposed common electrode 20. The plurality of signal electrodes 40 is exposed radially with respect to the center of cylindrical protrusion 12 to form B-phase signal electrodes. A-phase signal terminal 31 connecting to A-phase signal electrodes 30 and B-phase signal terminal 41 connecting to B-phase signal electrodes 40 extend downwardly from the outer peripheral wall and project from contact case 10 so as to sandwich common electrode 21 therebetween.
In operating shaft 50 made of an insulating resin, flange 52 is formed on the rear side of linear rod-like cylindrical part 51. Slider 60 is attached to flange 52 and slides on common electrode 20 and signal electrodes 30 and 40 of contact case 10 by rotating operation. At the center of flange 52, support 53 is projected. Support 53 is inserted and held in bearing hole 13 of contact case 10.
Bearing 70 has a fitting hole into which cylindrical part 51 of operating shaft 50 is inserted. The bearing is fixed to contact case 10 so as to include flange 52 therein and block circular recess 11 of contact case 10 from the front side thereof. Click spring 80 made of a resilient metal plate is fixed to bearing 70 on the side of contact case 10. A dowel at the tip of the resilient arm of the click spring is in resilient contact with projections and depressions provided on flange 52 of operating shaft 50.
Common electrode 20 and signal electrodes 30 and 40 are disposed on the bottom face of circular recess 11 of contact case 10 in a small angular range so as to reduce sliding abrasion and improve the durability of slider 60.
The rotationally-operated input device structured above is mounted on an insulating substrate (not shown) and an operating knob is attached to operating shaft 50. This rotationally-operated input device is rotated in parallel with the surface of the insulating substrate. A description of the operation thereof is provided hereinafter.
Rotation of operating shaft 50 causes slider 60 to slide on common electrode 20 and signal electrodes 30 and 40. This operation brings common electrode 20 and A-phase signal electrodes 30 into and out of electrical contact with each other via slider 60. Thus a rectangular wave signal is supplied between common terminal 21 and A-phase signal terminal 31. Similarly, this operation brings common electrode 20 and B-phase signal electrodes 40 into and out of electrical contact with each other via slider 60. Thus a rectangular wave signal is supplied between common terminal 21 and B-phase signal terminal 41.
A-phase signal electrodes 30 and B-phase signal electrodes 40 are displaced at a predetermined angle in the rotation direction of slider 60. Thus the A-phase rectangular wave signal and the B-phase rectangular wave signal are supplied with a phase difference. Therefore, according to the output state of the A-phase rectangular wave signal and the B-phase rectangular wave signal, a direction and amount of rotation can be detected. According to the detection, the function of the electronic device incorporating the input device is controlled.
For example, Patent Document 1 and Patent Document 2 are known as the information about conventional arts related to this invention.    [Patent Document 1] Japanese Patent Unexamined Publication No. 2004-219297    [Patent Document 2] Japanese Patent Unexamined Publication No. 2005-302654
However, with miniaturization and multi-functionality enhancement of electronic devices represented by a portable telephone, a rotationally-operated input device is requested to have a smaller mounting height and improved durability. For the above conventional rotationally-operated input device, slider 60 slides on common electrode 20 and signal electrodes 30 and 40 in a smaller angular range, but abrasion of slider 60 sliding on respective electrodes 20, 30, and 40 cannot be prevented. Thus there are limitations in increasing the life and reducing the height in the mounting state.